Supplementary Material (ESI) for Dalton Transactions
This journal is (c) The Royal Society of Chemistry 2010
Electronic Supplementary Information
Crystallographic Identification of an Unusual Homoleptic Palladium Citrate
[Na(OH2)6]⋅{[Na3(OH2)8]3[NaPd3(C6H4O7)3]2}⋅(H2O) Stabilised by Intermetallic
Aggregation with Sodium and Heavy Hydration
Parag Gunari,a Suresh s/o Krishnasamy,a Shi-Qiang Baia and T. S. Andy Hor*a,b
a
Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore
117543. Fax: (+)65-6873-1324. E-mail: andyhor@nus.edu.sg
b
Institute of Materials Research and Engineering, Agency for Science, Technology and Research,
3 Research Link, Singapore 117602
5-
O2
O
O
OH
OH
O
C2
O1
[C6H8O7]
C3
C1
HO
HO
Citric acid
PdCl2
NaHCO3
H2O
O7
O6
C6
O4
C5
[Na(OH2)6]{[Na3(OH2)8]3[NaPd3(
C6H4O7)3]2}(H2O) (1)
C4
C1
C6
O4
C4
O5
O3
Pd1
Pd1
O5 O3
O6
C5
O1
Na1
O7
O7
C3
C2
O2
C4 C1
Pd1 O3
O4
O1
C5
O5
C6
C2
C3
O2
O6
[NaPd3(C6H4O7)3]5- unit in 1
Scheme S1. One-pot formation of intermetallic supramolecular network of 1 from PdCl2 with
citrate in aqueous solution (left) and the C3-symmetric [NaPd3(C6H4O7)3]5− anion unit in 1 (right).
Supplementary Material (ESI) for Dalton Transactions
This journal is (c) The Royal Society of Chemistry 2010
Figure S1. a) 3-D structure of 1. b) [Na(OH2)6]+ complex was stabilised among two C3-symmetry
cavities by H-bond interactions in the network of 1.
Experimental section
NaHCO3 (0.5101 g, 6 mmol) was added to an aqueous solution of citric acid (0.39 g, 2 mmol) and
the mixture was stirred for 10 min to give a colorless solution, into which PdCl2 (0.1774g, 1
mmol) was added. The mixture was briefly swirled and then left standing overnight. It gradually
turned to a clear orange solution. Ethanol was added to precipitate a yellow solid which was
collected and redissolved in water and layered with ethanol to give orange crystals of 1, yield 1.3
g (near-quantitative based on Pd). 1H NMR (300 MHz, D2O): δ = 3.3159, 3.2638, 2.5965, 2.5461,
2.4749, 2.4639, 2.4240, 2.4119, (m, 2H, J = 15.6 Hz, CH2) 2.5965, 2.5461, 2.4749, and 2.4240,
(m, 2H, J = 15.1 Hz, CH2), 2.7 and 3.2 (d, 2H, H2O) 13C NMR: (75 MHz, D2O): δ = 45.4, 48.6,
49.4, 50.6, 57.4 for CH2, 75.1, 83.7, 84.7, 85.3 for CO, 176.8, 179, 179.9, 180.3, 181.7, 185.5 for
Supplementary Material (ESI) for Dalton Transactions
This journal is (c) The Royal Society of Chemistry 2010
CO2. Anal. Calcd. for dried sample (PdNa2C6H43/3O73/6 − H2O, lose one H2O per asymmetric
unit): C, 17.34; H, 2.99 %. Found: C, 17.31; H, 2.46 %.
X-ray crystallography
The measurement for 1 was conducted at r.t. on a Bruker AXS SMART APEX diffractometer,
equipped with a CCD area-detector using Mo-Kα radiation (λ = 0.71073 Å). The collecting
frames of date, indexing reflection and determination of lattice parameters and polarization
effects were performed with the SMART suite programs.1 The integration of intensity of
reflections and scaling was carried out by SAINT.1 The empirical absorption correction was
performed by SADABS.2 The space group determination, structure solution and least-squares
refinements on |F|2 were carried out with the SHELXS-97 and SHELXL-97.3 The structures were
solved by direct methods to locate the heavy atoms, followed by difference maps for the light
non-hydrogen atoms. O6S is situated at three fold axis, and the H atoms of O6S appeared to be
disordered and were not located. H atoms were located from difference map, refined with thermal
parameters following those of the atoms they were attached. OH distances were restrained. Pd is
coordinated to four O’s at about 2 Å and near to other Pd and Na at about 3.2−3.4 Å. O3 of the
citrate is disordered (76 : 24 occupancy ratio).
References:
1. SMART (Version 5.631) & SAINT (Version 6.63) Software Reference Manuals, Bruker
AXS GmbH, Karlsruhe, Germany, 2000.
2. G. M. Sheldrick, SADABS: a Software for Empirical Absorption Correction, University of
Göttingen, Göttingen, Germany, 2001.
3. (a) G. M. Sheldrick, SHELXS-97, Program for Crystal Structure Solution, University of
Göttingen, Göttingen, Germany, 1997; (b) G. M. Sheldrick, SHELXL-97, Program for
Crystal Structures Refinement, University of Göttingen, Göttingen, Germany, 1997.